1. Field of the Invention
The present invention relates to a radio wave receiver, a radio wave reception integrated circuit, a wave clock, and a repeater.
2. Description of Related Art
A standard radio wave including time data, that is, a time code is sent in each country (for example, Germany, England, Switzerland, Japan or the like). In our country (Japan), long wave standard radio waves the amplitudes of which are modulated by the time code of the standard time format, and the frequencies of which are 40 kHz and 60 kHz respectively, are sent from two transmitting stations (Fukushima and Saga). This time code is sent by the frame the cycle of which is 60 seconds, for every occasion when the place of minute of the exact time is updated, that is, for every 1 minute.
In late years, a so-called wave clock for receiving a standard radio wave including such the time code to correct the current time data by the standard radio wave has been put to practical use. The wave clock receives the standard radio wave via a built-in antenna for every predetermined time. Further, the wave clock amplifies and modulates the received standard radio wave and decodes the time code. Thereby, the wave clock corrects the current time.
Incidentally, the received signal that the wave clock actually receives is the standard radio wave sent from a transmitting station, to which various kinds of signals are mixed and superposed as noises in transmission process from the transmitting station to the wave clock. For this reason, there is possibility for misjudging the time data because of the noises included in the received signal.
Consequently, the method for removing noises from a received signal by using a filter such as a band pass filter, a low pass filter or the like is generally considered. However, a filter has a certain pass band, so that there has been the problem that a filter also allows passage of noise components in the vicinity of the received frequency (frequency of the standard radio wave) which essentially wants to pass the filter.